The present invention relates to a method for the manufacture of a color separation plate used for screen dot color printing, by thermal transfer recording.
With screen dot color printing that is used conventionally in magazines, newspapers and leaflets and the like, each of the colors of the photographic original are separated into the colors of yellow (Y), magenta (M) and cyan (C) or into these to which black (B) is added, and electric signals (color signals) corresponding to each of these colors are generated. Then, a plural number of color separation plates corresponding to each of the plural number of color signals is manufactured. Each color separation plate has screen dots recorded thereon, size of the screen dots corresponding to the density of one of those separated colors. After this, this plural number of color separation plates are used as the basis for the manufacture of machine plates corresponding to the plural number of colors and these are then overlaid to perform screen dot color printing.
These color separation plates are manufactured by exposing photographic originals onto a film through a screen dot filter and a color filter.
In addition, in one color separation plate manufacturing method that is recently used, the image is simultaneously enlarged, reduced or color-compensated by a scanner during color separation. Then, in the same manner as described above, color separation plates corresponding to the plural number of color signals are obtained by exposure.
In addition, in one extremely recent method for the manufacture of color separation plates, a scanner is used to perform color-separated image enlargement, reduction and color compensation on a computer screen. After this, using the scanner, color separation plates corresponding to the plural number of color signals are manufactured by exposing photographic originals onto a film.
The final check prior to screen dot color printing is performed using a test print from a machine plate. When the results of this final check indicate that various types of corrections are required, color separation plates corresponding to the plural number of signals must be remade. This requires a large amount of human labor and time and the plural number of color separation plates that are first made then become redundant. Furthermore, the manufacturing process becomes very expensive and there is much loss when urgency is required.
Currently, color printing technology is much more automated than it was in the past but the process for the development of the color separation plates using various types of liquids is still necessary. Because of this, there has been little progress in the facilities that are used for the process of developing the color separation plates.